Re: [PATCH 1/3] patch-ids: turn off rename detection

[Jacob Keller <jacob.keller@gmail.com>]

On Wed, Sep 7, 2016 at 3:02 PM, Jeff King <peff@peff.net> wrote:
> The patch-id code may be running inside another porcelain
> like "git log" or "git format-patch", and therefore may have
> set diff_detect_rename_default, either via the diff-ui
> config, or by default since 5404c11 (diff: activate
> diff.renames by default, 2016-02-25). This is the case even
> if a command is run with `--no-renames`, as that is applied
> only to the diff-options used by the command itself.
>
> Rename detection doesn't help the patch-id results. It
> _may_ actually hurt, as minor differences in the files that
> would be overlooked by patch-id's canonicalization might
> result in different renames (though I'd doubt that it ever
> comes up in practice).
>
> But mostly it is just a waste of CPU to compute these
> renames.

Yes this seems reasonable.

>
> Note that this does have one user-visible impact: the
> prerequisite patches listed by "format-patch --base". There
> may be some confusion between different versions of git as
> older ones will enable renames, but newer ones will not.
> However, this was already a problem, as people with
> different settings for the "diff.renames" config would get
> different results. After this patch, everyone should get the
> same results, regardless of their config.

Makes sense.

>
> Signed-off-by: Jeff King <peff@peff.net>
> ---
> The patch is the same as v1, but the commit message is modified, as I
> realized that "--base" does expose this value publicly (but as I argue
> above, this is probably an improvement).

I agree this is an improvement.

Thanks,
Jake